Effect of Impurities on Vacancy Mobility in V-4Cr-4Ti

Abstract:

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To investigate the effect of impurites, such as O, N and C, on migration behavior of
vacancies in several types of V-4Cr-4Ti vanadium alloy with different amount of impurites from 207wppm to 866wppm were irradiated with 28 MeV electrons using an electron linear accelerator at 100 K. After irradiation, positron lifetime measurements were carried out. Single vacancies were produced in all samples. The vacancy clusters were formed at 348 K and 433 K in samples with lowest and highest impurites, respectively. The temperature forming vacancy clusters incresased with increaisng amount of impurites. The vacancy migaration is depended on the amount of impurities rather than the kind of impurity.

Abstract: The crystallization and optimization of magnetic properties effects in FeXSiB (X=Cu, V,
Co, Zr, Nb) amorphous alloys were studied by applying X-ray diffraction methods, high resolution
transmission electron microscopy (HRTEM), resistometric and magnetic measurements. The
temperatures of the first and the second stage of crystallization, the 1h optimization annealing
temperature and the Curie temperature were determined for different amorphous alloys. Activation
energies of crystallization process were obtained by applying the Kissinger method. The influence
of alloy additions on optimization effect and crystallization processes was carefully examined.

Abstract: Effects of hydrogenation process of the microstructure, electrical conductivity and mechanical properties for the Cu-(1~3) mass%Ti alloys were investigated. During hydrogenation process at 350°C, 7.5 MPa for 48 h, the disproportionation reaction occurred with forming of Ti hydrides in the alloy. It is found that remarkable simultaneous improvements of mechanical strength of 1094 MPa and electrical properties of 21%IACS are obtained in the hydrogenated Cu-3mass%Ti alloy.

Abstract: Microstructural characterization of Al-Cu-Mg-Ag alloy ageing at low and elevated temperature were investigated by differential scanning calorimeter (DSC) and transmission electron microscopy (TEM). The results show that the precipitation sequence is significantly influenced by the ageing temperature. With prolonging of ageing at 65°C, G.P. zones on the plane of {100}α separates out with no precipitation of Ω phase. After 10h ageing at 160°C,the phase of Ω separates out and dominant the microstructure, while a small quantity of θ′separates out as well.

Abstract: Multiscale computational approach is used to evaluate microscopic parameters for description of nitride nuclear fuel. The results of atomistic simulation and thermodynamic modeling allow to estimate diffusivity and concentrations of point defects at various stoichiometric ratios of UN1+x. The diffusivities of Xe atom were calculated in various equilibrium states. In addition, we obtained the dependence of partial nitrogen pressure on x and temperature. The results of atomistic simulation were used for modeling of nuclear fuel behavior with use of mechanistic fuel codes.